The human lungs comprise a natural means for clearing mucus. Human lungs contain tiny clearing cilia that vibrate at approximately 18 Hz. At that frequency, mucus has a significant phase change from a viscous to fluid to thinner secretions. Accordingly, the cilia operate to loosen the mucus by making it more fluid. Once the mucus is more fluid, it can be more easily expelled.
Some patients with weak lungs, disease, or other ailments have lungs that cannot create a sufficient phase change in the viscous mucus. Additionally, a doctor may need to induce a sputum sample from a patient. Accordingly, an artificial means of vibrating the lungs at approximately 18 Hz can be used to supplement the patient's natural mucus system. In some cases, an artificial means of vibrating the lungs can produce the same phase change in mucus as produced by the lungs' natural cilia.
One conventional method for artificially vibrating a patient's lungs is by using pulses of air pressure introduced through the mouth and into the lungs. However, such a method can produce dangerously high air pressures, which can damage the fragile air sacs in the lungs.
Another conventional method for artificially vibrating a patient's lungs is by using low frequency audio of approximately 18 Hz to make lung secretions thinner. Low frequency audio does not induce potentially dangerous high air pressures in the lungs that are associated with the air pulses discussed above. However, conventional methods require very high audio power to cause vibration at low frequencies. Common loudspeaker components can be used to provide a high-powered audio source for vibrating the lungs. However, the life expectancy of the high-powered audio drivers is low, and the cost of the high-powered audio drivers is high. Additionally, powered subwoofers and loudspeakers typically are not disposable or portable.
A patient's lungs and vocal cords make a particularly efficient loudspeaker in the vocal range. However, low frequencies are not efficiently produced because both the vocal cords and the lungs are too small. If the lungs could be made larger, they would support low frequency audio production, and they also would couple efficiently to a low frequency audio source.
Therefore, a need in the art exists for a system and method that can provide a low-cost, disposable, and/or portable, artificial means of vibrating a patient's lungs to cause a viscous change in mucus contained therein. A need in the art also exists for an efficient means of coupling a patient's lungs with an audio source to produce a low frequency vibration in the lungs. Additionally, there exists a need in the art for a non-powered, low-frequency audio source for artificially vibrating a patient's lungs.